L34, Output-Side Circuit Breaker; General Information - Siemens SINAMICS S120 Equipment Manual

Options

8.19 L34, output-side circuit breaker

8.19 L34, output-side circuit breaker
8.19.1

General information

Availability of option
This option is available for the following S120 Cabinet Modules:
● Motor Module in chassis format
Description
The option L34 (output-side circuit breaker) can be used to disconnect the motor terminals
from the converter.
It is pre-wired and installed in a separate cabinet.
At the motor terminals, a rotating, permanent-field synchronous motor generates a voltage
that is proportional to the speed. The motor terminal voltage is always applied to the
converter output terminals, the DC link and the connected components. Option L34 can be
used to isolate a circuit in the event of a fault, or for maintenance work.
Note
Detailed and comprehensive instructions and information for the circuit breaker can be found
in the supplementary option description, which is available as additional documentation on
the accompanying customer CD.
The Option L34 (output-side circuit breaker) is required in the following applications where
permanent-field motors are used:
● Drives with a high moment of inertia, which require a longer period of time to coast down
● Mechanically coupled auxiliary drives, which can be driven together by a main drive.
● Maintenance and repairs on a converter if the motor cannot be stopped safely (e.g., by a
● During high field weakening in conjunction with a suitable level of overvoltage protection,
374
WARNING
and generate a voltage at the motor terminals during this time.
mechanical brake).
which suppresses the applied overvoltage effectively until the switch trips.
S120 Cabinet Modules Equipment Manual
Manual, (GH5), 10/2008, A5E00427098A